The object of the invention are colorants for keratin fibers, particularly human hair, that contain direct and/or oxidation dyes and a special thickener combination, as well as a method for coloring hair by use of such colorants,
Coloring preparations are usually in the form of aqueous—preferably thickened—solutions or emulsions and contain besides dyes, for example, fatty alcohols and/or other oil components, emulsifiers and surfactants as well as optionally alcohols. Oxidation dyes as a rule consist of two components (i) the dye carrier composition containing the dyes and (ii) the oxidation dye preparation, said components being mixed with one another shortly before use and then applied to the hair to be dyed. Mixing will produce a higher or lower viscosity, depending on the viscosity and mixing ratio of the two components. In particular, good adhesion of the colorant is achieved in this case if the colorant has a higher viscosity. In addition, the hair dresser often needs for her work higher viscosities, for example for special strand or sheet techniques and when special work is to be done with the dye brush or the highlighting brush.
Hence, a great need existed for economical thickening of the dye carrier composition that would ensure good miscibility of said dye carrier composition with the oxidant and would afford colorants with good adhesion properties and coloring characteristics.
The use of nonionic, amphiphilic associative thickeners for thickening hair colorants is known from WO 01/41723. The colorants described therein, however, are not satisfactory in all respects as regards their viscosity, adhesion to hair and coloring properties. For example, the viscosity-forming properties deteriorate after a storage period of only a few weeks. Moreover, the colorants described in WO 01/41723 have a honey-like consistency which allows the coloring composition to run off the hair. Another drawback is that high dye concentrations are incompatible with the associative thickeners.